JPH0212337Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Technical field of the invention] This invention aims to shorten the delay time (hereinafter referred to as running time) from the time when the voltage to the brake excitation coil is cut off to the start of braking in a spring-braking type DC electromagnetic brake that is attached to an electric motor, etc. This is about an old electromagnetic brake. [Prior art] Conventionally, in electromagnetic brakes using DC electromagnets, the above-mentioned lifting time becomes longer due to the effect of temporal changes in current due to the coil time constant of the excitation coil, making it necessary to stop in a fixed position, stop suddenly, etc. However, it has the disadvantage that its application is limited in some cases. To improve this point, the rapid excitation method is generally used.
Although an overexcitation type power supply circuit has been proposed, the power supply device is expensive, and this also has the disadvantage that its application is limited. [Summary of the invention] This invention was developed in consideration of the above points, and provides an electromagnetic brake that can shorten the hoisting time by improving the DC electromagnet itself. [Embodiment of the invention] An embodiment of this invention will be described below with reference to FIGS. 1 to 5. In Figures 1 and 2, 10
is a rotating shaft of an electric motor, and a hub 11 having a rectangular cross section is integrally fixed to one end of this rotating shaft 10, and a brake lining 12 is further attached to this hub 11 along the outer surface of the hub 11. Rotating shaft 10
It is loosely fitted and supported so that it can be slid in the longitudinal direction. Moreover, the fixed iron core 15 of this brake lining 12
A pressing plate 13 is disposed on the side end face, facing a fixed iron core 15 provided with an excitation coil 14 and a gap G in the axial direction of the rotating shaft 10 . Furthermore, fixing bolts 16 that loosely fit and support the pressing plate 13 in a slidable manner in the axial direction of the rotating shaft 10 are fixed to the fixed iron core 15 at required locations, and the brake lining 12 is attached to the open end of the fixing bolt 16. A brake plate 17 is fixed to be sandwiched between the press plate 13 and the press plate 13. This fixed iron core 15 has an outer pole 15a and an inner pole 15.
b, and its outer pole area S ₀ is larger than the inner pole area S _i , for example, 2 to 3 times larger, to constitute a DC electromagnet. The surface of the inner pole 15b is retracted from the surface of the outer pole 15a to form a concave shape. Braking springs 18 are respectively disposed in holes 19 provided at required locations in the fixed iron core 15, and act to press the pressing plate 13 toward the brake lining 12. In the electromagnetic brake of this invention configured as described above, at all times (when the power is OFF), the brake lining 12 is connected to the pressure plate 13 as shown in FIG.
and the brake plate 17 by the pressing force of the brake spring 18, thereby generating brake torque and braking the rotating shaft 10. In addition, fixed core 15
When the exciting coil 14 of A gap corresponding to the gap G is created between the press plate 13 and the rotating shaft 10 to release the brake. In a DC electromagnet, magnetic flux generally tends to gather inside the magnetic pole, and the effective magnetic pole area S _e changes depending on the configuration of the magnetic pole. In the braking state, magnetic flux gathers inside the magnetic pole due to the gap G between the fixed iron core 15 and the pressing plate 13 as shown in FIG. 3, and the effective magnetic pole area S _e
1 is small. On the other hand, in the brake release state, the pressing plate 13 is attracted to the fixed iron core 15, and as shown in FIG. 4, the magnetic flux is widely distributed, and the effective magnetic pole area S _e2
becomes larger. (Here, S _e2 > S _e1 ) Generally, the attractive force of an electromagnet is expressed by the following formula, and as the magnetic pole area S increases, the magnetic flux density B _g decreases,
The suction force F also becomes smaller. F=1/μB ² _g・S (here μ is magnetic permeability) Therefore, even if the same excitation coil is used, as the magnetic pole area increases, the attraction force during attraction will decrease.
When the electromagnetic brake is applied, the pressing force of the brake spring 18 overcomes the attractive force of the electromagnet, and the current value increases when the pressing plate 13 is released. As a result, as shown in Fig. 5, in the time change curve of the current when the voltage of the DC electromagnet is interrupted,
For the pressure plate release current i ₁ at the effective magnetic pole area S _e1 ,
The pressing plate release current i ₂ when the effective magnetic pole area S _e2 becomes high, and the feeding time t ₂ is shortened. Table 1 shows some of the data obtained from actual experiments and shows the significance of this idea.
Generally, the outer pole area/inner pole area ratio is often manufactured at or around 1/1, but by increasing the area ratio as described above, the loading time can be shortened.

[Effect of idea]

As explained above, in this invention, the outer pole area of the fixed iron core is made larger than the inner pole area to form a DC electromagnet, and the surface of the inner pole is made concave than the outer pole to form an electromagnetic brake. , it is possible to provide a high-performance electromagnetic brake that improves the operating characteristics (shortens the loading time) of the electromagnetic brake only by structurally improving the electromagnet, without using an expensive power supply. Further, due to the structure of the electromagnetic brake, fixing bolts, braking springs, etc. must be placed on the outer pole side, so by increasing the outer pole area, the magnetic poles can be used effectively.

[Brief explanation of drawings]

Figures 1 and 2 show an embodiment of the electromagnetic brake according to this invention, with Figure 1 being a cross-sectional side view, and Figure 2 showing the lower left portion of the center line taken along line A-A in Figure 1. , a front view showing the right part as a cross section taken along line B-B in Figure 1, Figures 3 and 4 are magnetic flux distribution diagrams, and Figure 5 is a temporal diagram of the current after the voltage drop in the DC electromagnet is interrupted. It is an operation diagram showing a change. In the figure, 10 is a rotating shaft, 11 is a hub, 12 is a brake lining, 13 is a pressing plate, 14 is an exciting coil, 15 is a fixed iron core, 16 is a fixing bolt, 17 is a brake plate, and 18 is a brake spring. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] A brake lining loosely fitted and supported by a hub fixed to a rotating shaft, a pressing plate disposed on an end face of the brake lining so as to be able to freely come into contact with and separate from it and sandwich the brake lining between the brake plates, and an outer pole. In the electromagnetic brake, the electromagnetic brake is composed of a DC electromagnet having an inner pole and releasing the pressing force of the pressing plate in the brake lining direction by electromagnetic force from an excitation coil, and a braking spring pressing the pressing plate in the brake lining direction. An electromagnetic brake characterized in that the outer pole area of a DC electromagnet is larger than the inner pole area, and the inner pole has a surface that is more concave than the outer pole.